Same thing happened to me, many of the passport pages had run - No problem for me as I self scan as a gold in the first wing and was only going to to Paris.

On the way back, the Immigration officer strongly advised me to get a new one. Some countries are very unforgiving and "think you may be trying to hide something".

Edit: Wow I sound like a complete DYKWIA! It's self scan at the normal security too isn't it possibly?!